A working group whose members include Humana, IBM, Johnson & Johnson, Merck, PepsiCo, Unilever, and South African insurer Discovery recently proposed that publicly traded corporations provide an overview on the health of their workforces in their various forms of public disclosure, including annual reports, 10-Ks, and sustainability reports.

Disclosures would include metrics collected through both screens (e.g., of weight, cholesterol, glucose, blood pressure, nicotine) and self-reporting of a variety of conditions (e.g., depression, anxiety, stress, alcohol consumption, eating habits). Other indicators of health — sleep, medication adherence, and exercise — could presumably be collected either through monitoring or self-reporting.

This working group is guided by the proposition that corporations should care about the health of their employees and, above all, not damage it. The group believes that just as more and more companies are disclosing their impact on the environment, companies should also disclose their impact on the health of their employees as well as other stakeholders. Measuring and reporting these employee health metrics is a first step in getting corporations to adopt programs to improve that impact, they say.

While I certainly applaud employers that try to provide positive working environments for their employees, my evaluation of this particular proposal is that there are problems with its assessments of its benefits and costs. I also believe that implementation would be difficult.

The benefits. One of the researchers involved in this proposal, Ron Goetzel of Johns Hopkins and Truven Health Analytics, coauthored a separate study that found that companies with award-winning wellness programs outperformed the stock market over a 14-year period. This study, which appeared shortly before the proposal was announced, forms the basis for the argument that shareholders would want to know about the health status of a company’s employees and wellness programs.

Publication bias aside, that study is controversial for three reasons. First, as I pointed out in this blog, benchmarking against sector indexes over a more recent five-year period yields the opposite result: companies with award-winning programs underperformed the average.

Second, as my coauthors and I pointed out in this recent article in The American Journal of Managed Care, there is no correlation between employee weight and a company’s financial success. Our conclusion was confirmed by a study published in Health Affairs showing that corporate weight-loss programs don’t generate clinically or statistically significant weight loss even if you pay your employees to lose weight. Ironically, Discovery’s own wellness program failed to lower the percentage of its employees who were “at risk” due to a high body mass index.

There is also a great deal of controversy about wellness programs and whether they add value for companies, and hence shareholders. Several Harvard-affiliated economists argued in a 2010 Health Affairs article that wellness programs produce a 3.27-to-1 return on investment. This finding was directionally confirmed (except for randomized control trials) by a meta-analysis conducted by a group at the University of Tasmania whose results were published in the American Journal of Health Promotion in 2014.

The costs. A biometric screen costs about $50 per employee, plus another $50 if spouses get screened. Pulling an employee off the job carries an expense as well. Consequently, such screenings would be expensive.

Beyond that, significant logistical questions must be addressed. Would employees be screened every year for all the metrics listed at the front of this essay? Most companies with wellness programs incentivize annual screenings now for all employees. Yet the United States Preventive Services Task Force (USPSTF) guidelines recommend against annual cholesterol and glucose screenings, particularly for younger adults, owing to the likelihood of false positives. The USPSTF recommends depression screening — but not annually, and only if “adequate treatment and appropriate follow-up” is available. But many employers might decide that other priorities, privacy concerns, and resource limitations preclude finding follow-up care for employees.

Implementation challenges. On a more practical level, how would employers get employees to participate? Participation in these screenings is low today despite incentives averaging $693. How much more can you pay (or fine) your employees to cooperate? What participation rates would be required to satisfy shareholders? Can a company say to its employees, “We have to weigh you because our shareholders want to know how fat we are”? That would be a difficult message to convey.

Then there are questions about which metrics to use. For instance, Discovery, whose Vitality Group unit designs wellness programs, reported a “cumulative” reduction of nearly 211 inches in waist circumference while simultaneously admitting that its average employee body mass index climbed. Which of those two measures should investors care more about? If a wellness vendor can’t reach a consistent conclusion for its own employee population, how can other corporations in other industries be expected to do so?

The challenges in reporting employees’ collective weight in a meaningful way pale when compared to those for reporting anxiety or stress. A scale for measuring stress that would be consistent with the rigor of other shareholder reporting metrics would have to be invented, but even that measurement would be straightforward compared to measuring depression. As far as I know, no company has ever tried to measure employee depression.

Discrimination and privacy. Assume for a minute that the study showing that companies with wellness programs outperform the stock market is correct. That would mean portfolio managers would drive up the prices of companies with a low percentage of overweight employees. What then happens to the employment prospects of overweight workers? Why wouldn’t a company try to shed as many overweight employees as possible and hire fewer new ones in order to maximize shareholder value? A Vitality executive assured STAT News that “existing laws” would protect overweight employees from discrimination, an opinion shared by a law firm that has written on this issue. (A history of case law on the topic can be found here.)

Many of the proposed health data points would be collected through employee self-reporting and would involve information that might be considered private. What would be the penalty for employees who lie about their carbohydrate or alcohol consumption? And how would sleep, exercise, and medication adherence be monitored? Self-reporting would be unreliable, but attaching monitors to employees and checking their prescription use could also be considered an invasion of privacy.

The report calling for employer disclosure of employee health information says investors should “exert pressure on companies to include health metrics as part of reporting, rewarding positive actions and penalizing inaction (or negative actions).” That is good for companies that help employers design and implement wellness programs. But is it desirable for employers, especially when wellness programs, according to industry leaders’ recommended budgets, could annually cost employers $100 to more than $300 per employee, and the lack of regulation, licensure, and oversight in this industry create a business environment that encourages vendors to flout clinical guidelines?

Perhaps a simple disclosure of whether employees are screened in accordance with USPSTF guidelines might be a better starting point. It would discourage inappropriate levels of mass screenings and show shareholders that employee health is of concern to management. Consistency with guidelines would also create consistency with the “first, do no harm” standard now applied to medical care generally. It wouldn’t require weigh-ins or other intrusive medicalizations of the workplace.

Additionally, this disclosure could force vendors to cut back on the expensive overscreening that is now commonplace. In that case, instead of being the most expensive disclosure ever, it would, ironically, become possibly the only disclosure of any type that actually saves money.

Al Lewis is a co-founder of Quizzify, a company that teaches employees how to buy and use health care.